Process for producing water gas free from tar and hydrocarbons



F. VOLK April 11, 1939.

PROCESS FOR PRODUCING WATER GAS FREE FROM TAR AND HYDROCARBONS Filed May 8, 1957 with tarry vapours and distillationgases.

certain purposes, however, such admixtures of the Patented Apr. 11, 1939 PATENT OFFICE PROCESS FOR PRODUCING: WATER GAS FREE FROM TAB AND HYDROCARBONS Franz Volk, Vienna, Austria Application May's, 1937, Serial No. 141,542

In Austria November 2, 1936 2 Claims. (Cl. 48-202) This invention relates to a process for producing water gas free from tar and hydrocarbons, from bituminous fuels. surmounted by a distilling chamber and con- 5 nected'to a superheater are already known. In such generators the fuel is carbonized or distilled by the hot water gas generated in the gasifying chamber of the generator and rising into the distilling chamber, whereby this water gas is mixed For water gas are objectionable and undesired. Moreover, in such generators the extent of the distillation of'the fuel depends on the sensible heat of the water gas produced in the gasifying chamber. With the useof fuelshaving a high degree of moisture or a low percentage of fixed carbon, this heat is not sufficient to effect a sufficient distillation of the coal.

It has been already proposed to generate the water gas in alternating directions and to exhaust by suction the volatile distillation products from the distilling chamber during the upruns and to pass these distillation products through the superheater into the fire zone of the gasifythis steam not being suflicient to dry and todistill the fuel in a satisfactory manner. Furthermore, in this period the steam is passed through the gasifylng chamber in the same direction as the fuel moves therethrough, whereby the steam is cooled at the upper cold fuel layers to such an extent that in the lower hot fuel zones the temperature gradient between the steam and the fuel, required for the heat transfer from the first to the latter is no more available.

By the present invention the production of a water gas free from tar and hydrocarbons, from bituminous fuels is made possible and the disadvantages of the methods known heretofore are obviated by distilling the fuel during the upruns as well as during the downruns by'means ,of a circulating gas stream, the water gas produced in the gasifying chamber being discharged from the generator separately from the distillation gases not decomposed. During the upruns Water gas generators 'per time unit may be regulated according to the 10 degree of moisture of the fuel and to theheat required for the distillation thereof so that it is possible to use fuels which are moist and difiicult to gasify, no condensation of tarry vapours or steam occurring in the upper cold fuel layers. 15 By the new process the distillation gases and therefore also the tar contained therein are decomposed to form water .gas. "In some cases, however, it may be desirable for the sake of economy to recover the tar contained in the coal instead of decomposing the same to water gas. This is effected by separating the tar from the circulating gas after the latter leaves the distilling chamber and before it enters into the superheater.-

If a tar production as complete as'possible is desired this production may be performed also during the hot air blast period by passing a portion of the blast gases through the distilling so chamber and then, mixed with the volatile distillation" products, through the tar separator in which the tar is separated, the residual gases passing through the superheater which is heated her 2 surmounted by the distilling chamber 2'.

3 designates a superheater working according to the regenerative principle and l designates a steam injector effecting the gas circulation. Instead of this injector however, a fan,or blower 45 of any desired construction may be provided.

, At first, the hot air blast period is'performed in the generator I by forcing air through the opened air valve 5 and the pipe 6 into the gasifying chamber 2. The blast gases flow through 50 the valve "I into the superheater 3 and are burnt in the latter by secondary air supplied from the pipe 8 through the valve 9 and, if required, also through the valve 9'. By this means the brick work of the superheater is heated up to a high 55 through the valve l2 and the pipe 6 into the gasifying chamber 2. In this chamber water gas is generated by the contact between the steam and the hot coke, this water gas being discharged from the generator through the valve i2 and the pipe it. At the same time the steam entering into the pipe I8 from the injector 4 exerts a suction action in the direction of the arrow 2:, whereby a gas circulation is caused along the elements 4, i5, 3, l2, 6, 2, 2', i4, 4. The volatile distillation products carried away by and with the circulating gas from the distilling chamber 2' are decomposed to water gas, as they pass through the fire zone of the gasifying chamber 2. The gas stream flowing from the gasifying chamber 2 into the distilling chamber 2 in the path of the circulation described above prevents the distillation gases coming from the distillation chamber 2' from being admixed with the water gas which is discharged at i3 from the generator I. On the other hand by this flow of the gases an amount of heat sufflcient for a complete distillationof the coal is transported into the distilling chamber 2', The intensity of the gas circulation and therefore also the amount of heat transferred into the distilling chamber 2' may be varied, as required, by regulating the pressure of the steam supplied to the injector 4, or when the fan or blower is used, by regulating the speed of the same.

Now follows-the downrun during which the valves i1 and I are opened and the valves i2 and I! closed. The steam supplied through ll, 4 and I passes now through the upper part of the superheacer 3 where it is superheated, and enters then through the valve 1 into the gasifying chamber 2 through which it passes from above to below. Thereby water gas is produced which leaves the generator i through the valve i1 and the pipe i6. At the same time, under the influence of the injector 4 a circulation is performed along the elements 4, i5, 3, 'l', 2, 2', i4, 4 whereby heat is transferred from the superheater 3 into the distilling chamber 2' and the fuel is distilled thereby. A portion of the distillation gases entering together with the steam through the valve I into the gasifying chamber 2 is branched 011 from the circulating gas andpasses through the gasifying chamber 2 from above to below. By this means not only the steam, but also the distillation gases are decomposed to water gas in the fire zone of the gasifying chamber, this water gas leaving the generator throughthe valve i'l. It will be seen therefore that also in this period the discharged water gas does not contain distillation gases.

If it is desired to obtain tar from the distillation gases a tar separator it of known construction inserted into the circular path between the distilling chamber 2 and the superheater 3 is set into operation. For this purpose the valves i9 and are opened and the valve i4 is closed. Alternatively, however, the injector or blower 4 may be omitted in which case the gas is circulated only by means of the blower l8. During the gas circulation which takes place in the uprun and downrun in the described manner the tar is separated from the circulating gas and is discharged from the accumulating device I! into a container (not illustrated) It is moreover possible to pass during the hot air blast period a portion of the blast gases from the gasifying chamber 2 through the distilling chamber 2' into the tar separator II and then, after freeing this portion from tar, through the injector 4 and the pipe i5 into'the superheater 3. In the latter the blast gases are burnt by means of secondary air supplied through the valve 9' and the combustion gases escape through the valve Ill.

What I claim is:

1. A process for producing water gas from bituminous fuels in a generator having a gasifying chamber and a superimposed distilling chamber, and having a superheater connected thereto, which comprises alternately hot air blasting, making a steam uprun and making a steam downrun, circulating during said uprun the gases from the distilling chamber through the superheater and the fire zone of said gasiiying chamber into the generator and discharging the water gas after having passed the gasifying chamber and before having entered into the distilling chamber, and circulating during said downrun the gases from said distilling chamber through said superheater into the generator at the junction zone between said both chambers and discharging the water gas after having passed the gasiiying chamber.

2. A process for producing water gas from bituminous fuels in a generator having a gasiiying chamberand a superimposed distilling chamber, and having a superheater connected thereto, which comprises alternately hot air blasting, making a steam uprun and making a steam downrun, passing during the hot blast period at least a part of the blast gases from the gasifying chamber through the distilling chamber, then separating the tar of the blast gases and finally admitting these gases into said superheater and burning them therein, circulating during said uprun -the gases from the distilling chamber through 

